Why Should I Have My Cat’s T-4 Checked ?

Hyperthyroidism is a common cat disorder in Joplin

Cats and malfunctioning thyroid glands have become common place. Hyperthyroidism is the state where the thyroid gland excessively produces thyroid hormone. Excessive thyroid hormone affects every organ in the cat’s body; excessive production is generally caused by developement of an adenoma (tumor) of the thyroid gland. While an adenoma is generally considered benign, the results of a thyroid adenoma are far from benign to the cat. Thyroid hormone increases the cellular metabolism of the body and speeds bodily functions. The increased metabolism causes weight loss and in some advanced cases results in an emaciated individual. The heart rate speeds up as the body metabolism increases often causing tachycardia (rapid heart rate) of 200 -240 bpm ( normal 120-160 ). Along with increased heart rate is the development of high blood pressure ( hypertension). The consequences of hypertension are multiple with damage to the kidney or progressing to kidney failure. Hyerpertension may also cause blindness from detached retinas or bleeding into the eye and vascular accidents which affect the brain, spinal cord , and other major organs. Cats that are middle aged to older are most commonly affected, but as a veterinarian I have seen cats as young as two years old with the disease.

What are the Symptoms?
The most common symptoms observed at home are unexplained weight loss and a ravenous appetite. However, frequently one primary complaint is vomiting. Others have poor appetites visual changes like blindness from high blood pressure detaching the retina in the eye. Therefore no one symptom can be associated with hyperthyroidism.

Diagnosis
It is fairly simple to test for hyperthyroidism through a blood test looking for an elevated T-4.. Many Joplin veterinarians as well as your Cornerstone veterinarianss are able to test T-4 in the office to receive answers quickly.

Treatment
There are multiple options for treatment.

Radioactive isotopes have been used to destroy the thyroid tissue. This method is very successful but requires the cat to stay at a specialized institution for about two weeks and is quite expensive.

Surgery is successful but is associated with potential life threatening complications for the first 48 hours.

Speicalized diet ( an iodine deficient diet Y/D) has been used with varying degrees of success. This diet must be fed exclusively, eliminating all other foods and treats. Without iodine, the cat is unable to manufacture thyroid hormone. Periodically the patient must be taken off the Y/D for a short time interval to provide enough iodine for the body to function.

Most often cats are treated with prescription medication available as either oral tablets or customized formulations which are applied to the inside ear flap skin. The medication works by blocking the production of T-4, thus eliminating the symptoms of hyperthyroidism. When the medicine is stopped however, symptoms will redevelop within 24 hours.

The veternarians at Cornestone have used all these methods with a high degree of success in even advanced cases as long as secondary disease is not present. While treatnment will improve cats with secondary disaease, such as renal failure, there usually are additional treatments required which alter the long term prognosis.

Recommendations
Prevention is always best. Cats that do not have any symptoms are easier to treat than cats that are already suffering from the disease. Thirty years ago, it was rare to see a cat with hyperthyroidism. The disease was primaryily seen on the east coast, and therefore it wasn’t deemed necessary to recommend routine screening. Currently in Joplin, we diagnosis cases of hyperthyriodism every month; the veterinarians at Cornerstone recommend cats be screened for elevated T-4 yearly.